WO2013100451A1 - Cmp slurry composition and polishing method using same - Google Patents

Abstract

The present invention relates to a CMP slurry composition and to a polishing method using same, wherein the CMP slurry composition of the present invention comprises: metallic oxide particles having a positive zeta-potential; a zwitterionic compound; a cationic surfactant; and ultrapure water.

Description

CMP slurry composition and polishing method using the same

The present invention relates to a CMP slurry composition and a polishing method using the same, and more particularly, to a CMP slurry composition comprising a metal oxide particle having a positive zeta value, an zwitterionic compound, and a cationic surfactant and a polishing method using the same. It is about.

Recently, microfabrication techniques have been developed in ultra large scale integrated circuits (ULSI), and design rules of 20 nanometers have been realized. In the manufacturing process of semiconductor devices, CMP technology has been spotlighted as an important technology that can stabilize the yield by finally flattening the layer on which exposure is applied by applying PR (Photoresist) to improve the precision of the pattern by exposure. . In particular, since the shallow trench isolation (STI) process is the first step in semiconductor processing with the most precise design, planarization after the STI process is the key to device formation.

Among them, the CMP slurry containing ceria particles is deposited on the gate generation site with a silicon nitride (Si ₃ N ₄ ), a trench isolation region, and a silicon nitride stacked in a thickness of 300 to 500 로 with an STI pattern mask. It has been in the spotlight as a main material for controlling the polishing rate selectivity between the (deposiotoned) silicon oxide film (SiO ₂ ).

In the STI process, a nitride mask is applied to a device generation site, and an oxide filled in a trench for device isolation may be over-deposited up to 7,000Å over the nitride film for complete filling.

At this time, a step of 2,000 to 3,000 kV occurs between the oxide film stacked on the nitride film and the oxide film overlaid on the trench of 2,000 to 2,500 kV. Referring to FIG. 1, STI CMP includes a primary polishing to remove a step between an overlaid oxide film (convex portion) on a nitride film and an oxide film (concave portion) on a trench, a secondary polishing to remove oxide on the nitride film, and a nitride film. In order to completely remove the residual oxide film, three steps of overpolishing are performed.

The primary polishing removes the oxide step quickly in consideration of productivity, and the secondary polishing is performed by polishing only 500 ~ 1000Å above the nitride layer in order to prevent the nitride layer from being polished and the oxide layer of the trench polished to a height below the nitride layer. Make a surface. The tertiary polishing is overpolishing so that the nitride film is polished to about 100 kPa or less so that the oxide film on the nitride film is completely removed, and the oxide film loss (dishing) of the trench should be minimized.

Ceria abrasives can exhibit twice as much polishing speed as silica abrasives requiring concentrations of 10% or more, even at low concentrations of less than 1% due to their strong reactivity with the oxide film. In recent years, it has been developed in the direction of reducing CMP defects such as the diameter of the particles is reduced to 100nm.

However, the ratio of the polishing rate to the oxide film of the trench upper layer to the oxide film of the trench layer can be maintained at 10 or more while maintaining the polishing rate for the oxide film existing in the nitride film upper layer at 10 or more, and at the same time dishing on the oxide film of the trench upper layer There is an urgent need for a CMP slurry composition that minimizes and minimizes defects on the entire abrasive layer.

An object of the present invention is to maintain the polishing rate of the oxide film present in the upper nitride layer at 3000 Pa or more, while maintaining the ratio of the polishing rate to the oxide film of the trench upper layer to the oxide film at 10 or more and at the same time dishing on the oxide film of the upper trench layer. It is to provide a CMP slurry composition that has minimized and minimized defect defects on the entire abrasive layer.

Still another object of the present invention is to provide a polishing method using the CMP slurry composition.

The CMP slurry composition of the present invention comprises metal oxide particles having a positive zeta potential, zwitterionic compounds, cationic surfactants, and ultrapure water.

The metal oxide particles may be prepared by calcination, flame oxidation, or thermal synthesis.

The metal oxide particles having the positive zeta potential are composed of ceria (CeO ₂ ) particles, silica (SiO ₂ ) particles, alumina (Al ₂ O ₃ ) particles, titania (TiO ₂ ) particles, and zirconia (ZrO ₂ ) particles. It may be at least one selected from the group.

The metal oxide particles having the positive zeta potential have an average particle diameter of 70 to 150 nm, and the specific surface area may be 10 to 50 m ² / g.

The metal oxide particles having the positive zeta potential may be ceria particles.

The zwitterionic compounds are alanine, phenylalanine, proline, glycine, histidine, histidine, lysine, arginine, threonine, aspartic acid. acid, tryptophan, glutamine, glutamine, betaine, cocomidopropylbetaine, cocomidopropylbetaine, and amino acid including at least one selected from the group consisting of laurylpropylbetaine Can be.

The cationic surfactants are triethylenetetramine, N, N-diethylethanolamine, N, N-diisopropylamine, N, N- It may be at least one selected from the group consisting of dietary butyl aniline (N, N-ditertiary butylaniline), and Lupasol (Lupasol).

The cationic surfactant may have a structural formula of Formula 1 below.

[Formula 1]

In Formula 1, EO is ethylene oxide, PO is propylene oxide, Q is hydrocarbon, and a, b, c, and d are each independently 0 to 50, e, f, g, and h. Are each independently 10 to 50, x is 0 to 15, and y is 0 to 1. If x = 0, it means that N and N are directly connected.

The weight average molecular weight of the cationic surfactant of Formula 1 may be 1,000 g / mol to 100,000 g / mol.

The CMP slurry composition may include 0.01 to 1% by weight of metal oxide particles, 0.001 to 1% by weight of zwitterionic compounds, 0.001 to 1% by weight of cationic surfactant, and ultrapure water as the balance.

The polishing method of the present invention includes polishing a semiconductor wafer using the CMP slurry composition.

The present invention maintains the polishing rate of the oxide film in the upper nitride layer at 3000 kPa or more, while maintaining a ratio of the polishing rate of the oxide film in the trench upper layer to the oxide film at 10 or more, while minimizing dishing on the oxide film in the trench upper layer. A CMP slurry composition is provided that minimizes the dug defects on the entire abrasive layer.

1 is a schematic process diagram of an STI process, which is one embodiment to which the composition of the present invention is applied.

FIG. 2 is a profile measured by AFM (Atomic Force Microscope) of the defects formed on the layer to be polished after the secondary polishing.

The CMP slurry composition of the present invention comprises metal oxide particles having a positive zeta potential, zwitterionic compounds, cationic surfactants, and ultrapure water.

Metal oxide particles

The CMP slurry composition of the present invention comprises metal oxide particles having a positive zeta potential.

As the metal oxide particles having the positive zeta potential, those produced by calcination, flame oxidation, or thermal synthesis are preferably used.

Metal oxide particles having a positive zeta potential include ceria (CeO ₂ ) particles, silica (SiO ₂ ) particles, alumina (Al ₂ O ₃ ) particles, titania (TiO ₂ ) particles, and zirconia (ZrO ₂ ) particles. Preference is given to using one or more selected from the group consisting of.

The metal oxide particles having the positive zeta potential have an average particle diameter of 70 to 150 nm and a specific surface area of 10 to 50 m ² / g in order to secure the polishing rate for the oxide film and to suppress the polishing rate for the nitride film. It is preferable.

The metal oxide particles having the positive zeta potential may be ceria particles, and in the case of using ceria particles prepared by hydrothermal synthesis, a dispersant may not be used. The zeta potential is maintained, so the oxide film polishing effect is excellent.

It is preferable to use the metal oxide particle which has the said zeta potential of the said amount in 0.01-1 weight%, and it is more preferable to use it in 0.1-0.7 weight%.

Zwitterionic compounds

The CMP slurry composition of the present invention contains a zwitterionic compound to block polishing of the nitride film.

The zwitterionic compounds are alanine, phenylalanine, proline, glycine, histidine, histidine, lysine, arginine, threonine, aspartic acid. acid), tryptophan, tryptophan, glutamine, glutamine, betaine, beta, cocomididopropylbetaine, and amino acid including one or more selected from the group consisting of laurylpropylbetaine. .

The zwitterionic compound is preferably used in an amount of 0.001 to 1% by weight relative to the total amount of the CMP slurry composition in order to secure the polishing rate for the oxide film, to suppress the polishing rate for the nitride film, and to minimize the defects on the entire polished layer. More preferably, 0.005 to 0.7% by weight, and most preferably 0.01 to 0.4% by weight.

Cationic surfactant

The CMP slurry composition of the present invention includes a cationic surfactant to adjust the polishing rate for the oxide film to improve the polishing profile, to minimize dishing on the oxide layer in the trench top layer and to minimize dug defects on the entire layer to be polished.

The cationic surfactants are triethylenetetramine, N, N-diethylethanolamine, N, N-diisopropylamine, N, N- Dibutyl butylaniline (N, N-ditertiary butylaniline), and may include one or more selected from the group consisting of Lupasol (Lupasol), preferably may include a compound having a structural formula of formula (1).

[Formula 1]

In Formula 1, EO is ethylene oxide, PO is propylene oxide, Q is hydrocarbon, and a, b, c, and d are each independently 0 to 50, e, f, g, and h. Are each independently 10 to 50, x is 0 to 15, and y is 0 to 1. If x = 0, it means that N and N are directly connected.

The weight average molecular weight of the cationic surfactant of Formula 1 is preferably 1,000 g / mol to 100,000 g / mol, and the viscosity is preferably 0.9 to 2.0 cP.

In the present invention, by using the cationic surfactant simultaneously with the zwitterionic compound, it is possible to minimize dishing on the oxide layer of the trench upper layer and to minimize dug defects on the entire layer to be polished.

The cationic surfactant adjusts the polishing rate for the oxide film to improve the polishing profile, to suppress the polishing rate for the nitride film, to minimize dishing on the oxide layer of the trench upper layer, and to minimize the pit defects on the entire polished layer. It is preferable to use it at -1 weight%, It is more preferable to use it at 0.005 to 0.8 weight%, It is most preferable to use it at 0.01 to 0.7 weight%.

The polishing method of the present invention may include polishing a semiconductor wafer using the CMP slurry composition. The process may be an interlayer dielectric (ILD) process or a shallow trench isolation (STI) process. At this time, since the CMP slurry composition of the present invention has excellent polishing efficiency with respect to the patterned oxide film, the semiconductor wafer to be polished preferably includes the patterned oxide film.

The present invention will be described in more detail with reference to the following Examples. However, this is only possible embodiments for description, and the present invention is not limited thereto.

Example 1

In Formula 1, Qx (x = 2) is ethylene, y = 1, (a + b + c + d) / (e + f + g + h) is 1.5 and the cationic interface has a weight average molecular weight of 10,000 g / mol. A weight average molecular weight of 10,000 g / mol having an average particle diameter of 100 nm (measured by Horiba LA710) of 0.5% by weight of the active agent (a) and 0.2% by weight of the zwitterionic compound L-Aspartic acid (c) Aqueous dispersion with phosphoric polyacrylic acid and 0.5 wt of ceria having a zeta potential of 40 mV were mixed with ultrapure water to prepare a sample. One-part slurry was produced by adjusting pH to 4.5. According to the polishing conditions, the polishing performance of the pattern wafer having the pattern density of 50% and the pitch size of 100 μm was evaluated, and the results are described as shown in Table 1.

Example 2

Samples were prepared in the same manner as in Example 1 except that 0.05% by weight of laurylpropylbetaine (f) was used instead of L-Aspartic acid (c), and the polishing performance was evaluated. It is shown in Table 1.

Example 3

Instead of the cationic surfactant (a), Qx (x = 2) is a cationic surfactant (b) having ethylene, y = 1, a, b, c, d is 0 and a weight average molecular weight of 10,000 g / mol. A sample was prepared in the same manner as in Example 1 except that it was used, and the polishing performance was evaluated.

Example 4

Samples were prepared in the same manner as in Example 2, except that cationic surfactants (a) were used instead of cationic surfactants (a), and the polishing performance was evaluated and listed in Table 1.

Comparative Example 1

In Formula 1, Qx (x = 2) is ethylene, y = 1, (a + b + c + d) / (e + f + g + h) is 1.5 and the cationic interface has a weight average molecular weight of 10,000 g / mol. 0.5 wt% of the active agent (a) and 100 nm (measured by Horiba LA710) with a weight average molecular weight of 10,000 g / mol of polyacrylic acid were dispersed in water and 0.5 wt% of ceria having a zeta potential of -30 mV was mixed with ultrapure water. Was prepared. One-part slurry was produced by adjusting pH to 4.5. According to the polishing conditions, the polishing performance of the pattern wafer having the pattern density of 50% and the pitch size of 100 μm was evaluated, and the results are described as shown in Table 1.

Comparative Example 2

A sample was prepared in the same manner as in Comparative Example 1 except that ceria having an average particle diameter of 100 nm (measured by Horiba LA710) and a zeta potential of +40 mV was used instead of the ceria of Comparative Example 1, and the polishing performance was evaluated. Described.

Comparative Example 3

Instead of the cationic surfactant (a), Qx (x = 2) is a cationic surfactant (b) having ethylene, y = 1, a, b, c, d is 0 and a weight average molecular weight of 10,000 g / mol. Except for the use, samples were prepared in the same manner as in Comparative Example 2, and the polishing performance was evaluated and listed in Table 1.

Comparative Example 4

Samples were prepared and polished in the same manner as in Comparative Example 2, except that 0.2% by weight of L-Aspartic acid (c), which is an ionic compound, was used without a cationic surfactant. It evaluated and is shown in Table 1.

Comparative Example 5

A sample was prepared in the same manner as in Comparative Example 4 except that glycine (d) was used instead of L-aspartic acid as the zwitterionic compound, and the polishing performance thereof was shown in Table 1 below. .

Comparative Example 6

A sample was prepared in the same manner as in Comparative Example 4 except for using Lysine (e) instead of L-Aspartic acid as the zwitterionic compound, and the polishing performance was shown in Table 1 below. .

[Measurement Method]

Dig defect: It is visually identified on the oxide film and nitride film. It is observed as visual stain. When AFM is measured, the spot is measured with a step of 400Å ~ 800Å compared to the surrounding area. Determination of the deficiency was determined visually or absent.

Polishing rate (Å / min): Convex Ox RR means the polishing rate for the oxide film on the upper nitride layer, Convex SiN RR means the polishing rate for the nitride layer, and concave Ox RR is the upper trench Means the polishing rate for the oxide film.

The patterned wafer was polished under the following polishing conditions using the CMP slurry composition prepared in the above Examples and Comparative Examples. The polishing rate was calculated by measuring the change in thickness of the wafer removed by polishing, and measured using an Optiprobe (ThermalWave, Optiprobe2600) equipment.

[Polishing condition]

Patterned Wafer: 200 mm Massachusetts Institute of Technology (MIT) pattern wafers first polished with a commercial slurry (Cheil Industries SP7500).

Polishing Equipment: AMAT Mirra (AMAT Co.)

Polishing pad: IC1010 k-groove (Rodel)

Polishing time: P1 60 sec, P2 30 sec, P3 40 sec

Polishing Pressure: 3psi

Platen rpm: 103 rpm

Head rpm: 97 rpm

Flow rate: 200 ml / min

TABLE 1

As can be seen from the above results, the CMP slurry composition of the present invention maintains the polishing rate of the oxide film in the upper layer of the nitride layer to 3000 or more, while maintaining the ratio of the polishing rate of the trench layer to the oxide film of the nitride layer to 10 or more. At the same time, it can be seen that the dug defects on the entire abrasive layer are minimized.

Claims (10)

1. Metal oxide particles having a positive zeta potential;

   Zwitterionic compounds;

   Cationic surfactants; And

   CMP slurry composition comprising; ultrapure water.
2. The CMP slurry composition of claim 1, wherein the metal oxide particles are prepared by calcination, flame oxidation, or hydrothermal synthesis.
3. The CMP slurry composition of claim 1, wherein the metal oxide particles are at least one selected from the group consisting of ceria particles, silica particles, alumina particles, titania particles, and zirconia particles.
4. The CMP slurry composition according to claim 1, wherein the metal oxide particles having a positive zeta potential have an average particle diameter of 70 to 150 nm and a specific surface area of 10 to 50 m ² / g.
5. The CMP slurry composition of claim 1 wherein the metal oxide particles having a positive zeta potential are ceria particles.
6. The method of claim 1, wherein the zwitterionic compound is alanine, phenylalanine, proline, glycine, histidine, lysine, arginine, threonine ), Aspartic acid, tryptophan, glutamine, glutine, betaine, cocomidopropylbetaine and laurylpropylbetaine. CMP slurry composition, characterized in that the containing amino acid.
7. The method of claim 1, wherein the cationic surfactant is triethylenetetramine, N, N-diethylethanolamine, N, N-diisopropylamine ), N, N-dibutylbutylaniline (N, Nditertiarybutylaniline), and Lupazole (Lupasol) CMP slurry composition comprising at least one selected from the group consisting of.
8. The CMP slurry composition of claim 1, wherein the cationic surfactant has a structure of Formula 1

   [Formula 1]

   

   In Formula 1, EO is ethylene oxide, PO is propylene oxide, Q is hydrocarbon, and a, b, c, and d are each independently 0 to 50, e, f, g, and h. Are each independently 10 to 50, x is 0 to 15, and y is 0 to 1.
9. The method of claim 1, wherein the CMP slurry composition is 0.2 to 0.5% by weight of the metal oxide particles having the positive zeta potential, 0.001 to 1.0% by weight of zwitterionic compounds, 0.0001 to 0.5% by weight of cationic surfactant and the residual amount of ultrapure water CMP slurry composition comprising a.
10. A polishing method comprising polishing a semiconductor wafer using the CMP slurry composition of any one of claims 1 to 9.

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